A great number of finished leather products require maintenance polishes to preserve, clean and water-proof them. Footwear, in particular, requires a leather-care product that helps prevent the leather from drying out and forming unsightly cracks in the creases of the shoe uppers. Shoe polishes, therefore, are used to impart a high-gloss, maintain the supple hand of the leather, and increase the leather's resistance to weathering, scuffing and scratching.
One of the problems of conventional shoe polishes is providing, on a flexible surface, a protective finish which is both lustrous, durable, and water-resistant. The majority of shoe polishes are of the solvent paste type based on solvents and waxes. While solvent pastes clean the shoe well while the paste is being applied, the resulting film dries to a dull finish and must be buffed to produce a high natural shine. A further disadvantage of the solvent paste polishes is that the protective effect they produce is only temporary. Consequently, they must be applied frequently in order to properly protect the footwear leather.
Another disadvantage of a wax-based shoe polish is that the finish tends to deluster on exposure to moisture from rain, water splashing or puddles. Additionally, layers of wax can build up on the leather surface. This resulting buildup resists subsequent reapplications of polish, thus extensive buffing is required in order for a new layer of polish to properly "take" on the leather.
Some attempts have been made to overcome the drawbacks of solvent paste polishes by formulating emulsion cream polishes. These polishes are emulsions of waxes, solvents and water. However, the finish produced suffers from the same drawbacks as those obtained from other wax-based polishes.
Further attempts to overcome the drawbacks of wax-based polishes include the formulation of self-polishing or dry-bright liquids. Self-polishing liquids are generally comprised of a blend of a fairly soft acrylic polymer emulsion, a rosin adduct leveling resin, a wax emulsion (frequently a low molecular weight polyethylene emulsion) and modifiers, such as a leveling plasticizer and a coalescing solvent. The ratio of polymer/resin/wax is varied depending on the degree of buffability desired. Usually, a higher wax content gives the polish better buffing properties. The liquid polishes clean the shoes well, particularly when they are applied with foam sponge applicators which provide abrasive cleaning. The emulsions apply a film of glossy polish that, in most cases, does not require buffing to obtain a high shine. However, the shine produced tends to have an unnatural, plastic-like appearance.
Thus, there is a need for self-polishing liquids and emulsion cream products that provide a flexible finish coating having a natural high gloss that is durable and scuff-proof.